In a wireless network, the transmission medium may be inherently lossy and susceptible to interference. To better ensure reliable communications in a wireless network, the receiver may be required to acknowledge every message that is received so that the sender may be notified when messages are properly received, and have the opportunity to retransmit an unacknowledged message. Such a method of acknowledged communication has been implemented, for example, in a unicast communication scheme, where the sender sends a message to only one receiver and expects only one acknowledgement of the receipt the message. In a broadcast or multicast communication scheme, however, where the sender sends a message to more than one receiver and expects multiple acknowledgements, such a method may be problematic and/or inefficient.
For example, there is the scenario in which each node of a wireless network is equipped with a temperature sensor, and a query is to be made as to which sensors are currently reading a temperature in a particular range. In this case, the query message is first broadcasted to all nodes in the network, then each node is required to reply back with its own reading or status, but such replies may require significant resources to handle.
As another example, there is the scenario where each node of the wireless network is equipped with an alarm sensor, and a command is to be issued to collectively arm/disarm the sensors. In this case, the command message may be issued via a base station, which is sent to all nodes in the network, then each node is required to reply back indicating whether the command was successfully executed or not, but as in the previous example, such replies from all of the nodes may require significant resources to handle.
Latency may also be an issue with respect to acknowledged communications. Here, it may at least be a challenge to ensure that all nodes in the network receive the message/command and respond appropriately in a reliable and timely fashion, and that all responses from the nodes are also received and processed in a reliable and timely fashion. In this regard, the collection and processing of responses by a central node, for example, such as a base station, may be a particular challenge.